Police in Santa Ana, Calif., announced yesterday that a former Marine's pick-up truck and custom-fit prosthetic leg were stolen from the parking lot of Knott's Berry Farm last month.

Juan Hernandez, 53, went to the amusement park with his family on May 26, a day intended to honor military personnel. Instead of using his prosthetic leg, Hernandez opted to use a wheelchair, he says, leaving the leg in the back seat of his truck. When Hernandez returned, he discovered that his blue Chevrolet pick-up was gone. "They probably didn't realize what was in the truck," Hernandez told ABCNews.

Now police say they are looking not only for the person who stole the truck but for the man who caused Hernandez to lose his leg three years ago in a gang-related incident.

Hernandez told ABC News that the leg, valued at around $50,000, was given to him after his story appeared on "America's Most Wanted" in 2012.

In 2010, Hernandez was almost killed after being repeatedly run over by a truck on Thanksgiving Daywhen he tried to intervene in a fight between local gang members who were tagging a wall near his house in Santa Ana and his son, who was trying to stop them.

"[Hernandez] was trying to stop the fighting. The gang members left and then came back with more people. That's when our primary suspect ran over Hernandez," Corporal Anthony Bertagna of the Santa Ana Police told ABCNews.

Bertagna said the suspect, Jose Luis Berruette, ran his truck into Hernandez and then his car got stuck on a brick wall. Berruette then went "back and forth," said Bertagna, repeatedly trying to get off the wall, running over Hernandez multiple times. His injuries resulted in his leg's being amputated from the knee down. Berruette has not been caught.

Bertagna told ABCNews that he believes Berruette is now going by a different name, Luis Avilla, and is smuggling drugs and people across the border between Mexicali and Orange County.

"[Hernandez] is really lucky to be alive," said Bertagna.

Although Hernandez's truck was stolen, he said he really only cares about getting his leg back.

"I could walk. The leg made me feel normal," Hernandez explained. "If they want the truck that's fine, but my leg is going to be hard to replace. It was so comfortable and it really was the perfect fit. It's depressing now. This set me back to the accident because now I'm crippled again."

Despite his trials, Hernandez remains optimistic about his future.

"It's not all bad. There are some good things in life and I have a lot to be thankful for," said Hernandez, who has 11 grandchildren.

Hernandez also asked for everyone to be on the lookout for his leg so he can get back to his normal life.

"Please have a heart. That leg means a lot to me," said Hernandez. "Please contact someone if you see my leg and I will be very thankful."